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CROSS Safety Report

Plastic composite fencing

Report ID: 1034 Published: 26 August 2022 Region: CROSS-UK


Overview

A reporter is concerned about the possibility of fire spread between buildings when the external plastic composite fencing is involved in a fire.

Key Learning Outcomes

For specifiers, designers, procurement:

  • Composite fence elements, and similar decking products, are vulnerable to fire exposure and can assist fire to spread to other buildings
  • It can be considered good practice and common sense on the side of those who are responsible for safety to consider the risk posed by these products where they are placed externally
  • The production of smoke during a fire, and its toxicity, can pose serious risks to the safety of the building occupants, area residents, and emergency responders, along with any potential environmental concerns

For landlords and housing managers:

  • Consider contacting your local Fire and Rescue Service so that appropriate advice can be provided on the issue

Full Report

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A reporter is concerned about the possibility of fire spread between buildings when the external plastic composite fencing is involved in a fire.

Composite fencing is usually comprised of a synthetic product that uses wood and plastic as its primary materials. They have also been referred to as ‘plastic wood’. These products are made in factory conditions where the wood fibres and plastic are mixed with an adhesive and undergo heat treatment. This process results in a durable, lightweight, and aesthetically pleasing composite product. Because wood fibre and plastic are often recycled materials, this also makes these composite products attractive as an eco-friendly solution.

Because of their low-maintenance needs, composite decking products are becoming a popular alternative to wooden solutions for fencing, decking, balconies, benches, sheds, stores, smoking shelters, and children’s playground equipment. Due to their usual field of application, they are not considered construction products and therefore their desired properties are not explicitly covered in technical guidance.

The reporter informed CROSS that there have recently been two serious fire incidents, in which the composite decking was the medium in a fire that externally bypassed compartment party walls of terraced houses, eventually spreading fire to multiple dwellings. The high rate of fire spread, the intensity of burning, along with the thickness and acridity of the smoke were also highlighted as noteworthy.

composite decking was the medium in a fire that externally bypassed compartment party walls of terraced houses

Expert Panel Comments

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Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

The panel considers that the reporter raised a very interesting point. Composite decking products have been the focus of previous reports in two cases; once in report 1048 where they were used to form the common access balcony, and in report 1095 where information on their expected performance or its certification would not be provided.

However, decking used on a balcony for a flat would be covered by Building Regulations, whereas the cases described in this report seem to relate to external garden decking outside the building which would not be subject to Building Regulations (or any other fire safety regulations). It should be noted, however, that some cases may well be covered under current fire safety law if the external products form part of the means of escape on the ground floor where there is only one exit from a premises. Ideally, there could be guidance covering the safe use of composite garden decking, but currently there is no regulatory way to prevent it.

Even if it may not be a 'legal requirement', it can be considered good practice and common sense on the side of those who are responsible for safety (in the event of fire) to consider the risk (flames/heat/smoke) posed by these products where they are placed externally. That is also because the production of smoke during a fire, and its toxicity, can pose serious risks to the safety of the building occupants, area residents, and emergency responders, along with any potential environmental concerns.

Another issue which is outstanding is an assessment of the importance of this specific issue, when compared to other combustible materials that might be stored next to a house, such as sheds, pergolas, piles of rubbish, and more. As the reporter mentioned, the speed of spread is a concern, but it is expected that people would be able to use internal escapes to evacuate away from the fire towards a place of safety. Similarly, one of the potential key risks in the case of composite decking is smoke and toxicity which is also not explicitly included in Building Regulations but can affect the region’s air quality and can have environmental implications.

We note the reporter's recommendation that there should be a 5m (15ft) separation zone and whilst agreeing that this might be a sensible precaution there is no published evidence to support a specified distance. Landlords and housing managers should become aware of this issue and follow the relevant advice issued by their local Fire and Rescue Service.

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